lèi / dì / xíng / xīng / tōng / cháng / yóu / yán / shí / hé / jīn / shǔ / zǔ / chéng / ér / bú / shì / zhǔ / yào / yóu / qì / tǐ / zǔ / chéng

类地行星通常由岩石和金属组成，而不是主要由气体组成。

Terrestrial planets are usually made of rock and metal rather than being composed mainly of gas.